Android :: Application Shutdown During Package Reinstall

I'm working on the upgrade process for an Android app and am having a hard time ensuring a graceful shutdown of the old version. Can someone explain how the old version of the app is killed and if there is anything we can do to hook into the process? In more detail:

We notice that a new version of our app is available and launch a new activity with Intent.ACTION_VIEW pointing to the new apk file (or to the marketplace, once our app is there). However, the user has 2 chances to abort the install (once at the warning about reinstalling the app, and the second when warned about the permissions our app needs). My understanding is that I can't use startActivityForResult() with ACTION_VIEW, so I can't find out if the Action is aborted or not. So we can't tell if/when the install has been started.

We'd like to ensure that our app shuts down cleanly since we use a lot of native code and threads. We could kill our app proactively, as soon as we launch the ACTION_VIEW activity, but then we're left in a bad state if the user aborts. We could wait for the installer to remove our files, prior to installing the new version, but that's a hack. Is there any clean way to do this? Our main window is never seeing an onDestroy(), btw.